How to widen the bevel width?
The top face is an n-gon (it's defined by more than 4 vertices) and problems with beveling n-gons are to be expected. You can move the n-gon inside, by selecting that face and insetting it. As you move it toward the middle, you will experience a different issue, where the edges are going to intersect, so at some point you stop insetting (click to accept), and then scale the face down to further decrease it. Now there's plenty of room using quad topology for the bevel.